 
#include "stack.h"  
int main(int argc, char *argv[]){  
    ST * stack = createStack();
     pushStack(stack,'a');
    pushStack(stack,'b');
     pushStack(stack,'c');
     pushStack(stack,'d');
     printf("%c \n",popStack(stack));
    for (size_t i = 0; i <= stack->data_size; i++)
    {
         printf("%c \n",popStack(stack));
    }
     printf("%d \n",stack->data_size);
    return 0;  
}
